30 Days of Distinct Artifacts :Count Unique Artifacts Sold by Category in the Last 30 Days Intermediate

          with recentsales as
  (select distinct od.productid,
                   p.category
   from orderdetails od
   join products p on od.productid = p.productid
   join orders o on od.orderid = o.orderid
   where o.orderdate::timestamp >= current_date - interval '30 days' )
select distinct category,
                count(productid) over (partition by category) as distinctartifactssold
from recentsales;